Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 207,492	$ 687,419
Adjustments to reconcile net income to net cash provided by operating activities:
Decrease (increase) in premiums receivable	(252,609)	(174,583)
Decrease (increase) in funds held by reinsureds, net	(23,498)	(55,421)
Decrease (increase) in reinsurance receivables	(147,515)	(19,319)
Decrease (increase) in income taxes	(25,000)	180,126
Decrease (increase) in prepaid reinsurance premiums	(29,699)	(137,092)
Increase (decrease) in reserve for losses and loss adjustment expenses	800,816	155,096
Increase (decrease) in future policy benefit reserve	(1,933)	(1,648)
Increase (decrease) in unearned premiums	159,744	219,263
Increase (decrease) in other net payable to reinsurers	89,499	132,474
Increase (decrease) in losses in course of payment	147,427	35,738
Change in equity adjustments in limited partnerships	84,066	(57,031)
Distribution of limited partnership income	40,447	41,321
Change in other assets and liabilities, net	(10,313)	(60,820)
Non-cash compensation expense	19,175	17,171
Amortization of bond premium (accrual of bond discount)	20,547	13,321
Net realized capital (gains) losses	25,940	(122,504)
Net cash provided by (used in) operating activities	1,104,586	853,511
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from fixed maturities matured/called - available for sale, at market value	1,261,650	1,009,921
Proceeds from fixed maturities sold - available for sale, at market value	990,273	2,318,207
Proceeds from fixed maturities sold - available for sale, at fair value		2,706
Proceeds from equity securities sold, at fair value	213,185	149,233
Distributions from other invested assets	164,975	143,752
Cost of fixed maturities acquired - available for sale, at market value	(2,301,701)	(3,466,331)
Cost of equity securities acquired, at fair value	(224,086)	(229,070)
Cost of other invested assets acquired	(343,332)	(207,323)
Net change in short-term investments	(439,457)	(499,983)
Net change in unsettled securities transactions	49,504	88,531
Net cash provided by (used in) investing activities	(628,989)	(690,357)
CASH FLOWS FROM FINANCING ACTIVITIES:
Common shares issued during the period for share-based compensation, net of expense	(12,841)	(7,485)
Purchase of treasury shares	(200,019)	(24,604)
Dividends paid to shareholders	(125,205)	(114,136)
Cost of debt repurchase	(10,647)
Cost of shares withheld on settlements of share-based compensation awards	(14,141)	(11,748)
Net cash provided by (used in) financing activities	(362,853)	(157,973)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	1,699	91
Net increase (decrease) in cash	114,443	5,272
Cash, beginning of period	808,036	656,095
Cash, end of period	922,479	661,367
SUPPLEMENTAL CASH FLOW INFORMATION:
Income taxes paid (recovered)	10,895	(83,995)
Interest paid	$ 14,992	$ 15,984